The proposed Breast and Women's Cancer Laboratory (BWCL) is a 12,435 net square foot facility devoted to basic and translational research at the University of California, Irvine (UCI), College of Medicine. The proposed construction would complete shell space in the lower level of Sprague Hall to house a core group of women's cancer researchers with strong collaborative ties to a larger effort in women's cancer. Despite an aggressive building program, faculty recruitment and increased PHS funding have outpaced the availability of laboratory space. Since 1998, the College of Medicine has recruited 24 professors and 34 researchers, an increase of 16% and 100% respectively. The School of Biological Science has experienced comparable growth, adding 23 professors or 33% to its faculty. The proposed project would augment campus construction to help accommodate this rapid growth in biomedical research activity, specifically in breast and women's cancer. The BWCL would house the laboratories of seven investigators and their collaborators. The laboratory space also would serve as a resource for a group of secondary users, defined as researchers collaborating and sharing facilities such as the Laser Optics Lab. The proposed facility would gain efficiencies from existing shared resources such as darkroom, glasswash, offices, large conference and break rooms in the upper floors, and have excellent access by tunnel to the existing Gillespie Vivarium, including a new Genetically Modified Rodent Facility, being constructed under a separate NCRR grant.